House Speaker Paul Ryan (R-Wisconsin) invoked freedom of religion in the United States as he criticized Donald Trump’s call for the U.S. to ban all Muslims from entering the country.

(J. Scott Applewhite/AP)

"This is not conservatism. What was proposed yesterday is not what this party stands for and more importantly it's not what this country stands for," the Wisconsin Republican said at a press conference with House GOP leaders.

The normally mild-mannered Ryan seemed barely able to contain his fury as he pointed out that he rarely comments on remarks from the GOP field — but had to make an exception to push back against his party's current presidential front-runner.

Donald Trump released a policy proposal on Monday that aims to ban all Muslims from entering the United States, including Muslim-Americans who may have traveled abroad.

"Freedom of religion is a fundamental constitutional principle. It's a founding principle of this country," Ryan said before pointing out that loyal Muslims serve in the military and in Congress and "some of our best and biggest allies" are Muslim-heavy countries.

When asked if he was worried Trump's abhorrent comments could hurt his party, Ryan said he was more worried about defending American values than politics.